This invention relates to the production of potato chips of relatively low oil content and yet which have taste and texture which is indistinguishable from regularly prepared potato chips.
Conventional potato chip products are prepared by the basic steps of slicing peeled raw potatoes and frying them in oil at 350.degree. F. to 380.degree. F. for 2 to 4 minutes, or until a moisture content of approximately 1%-2% by weight is achieved, for example, by frying for 3 minutes at 350.degree. F. The fried chips are then salted and packaged.
The moisture content of raw potato slices normally is from 75% to 85%, depending on environmental growing conditions and varieties. When potato slices are fried in oil at high temperature, this substantial amount of moisture present boils explosively. This results in burst cell walls, and consequently, the formation of capillary holes and voids. Oil adheres to the surfaces of the chips and is also absorbed into the holes and voids in the slices, particularly if they leave the frying oil, are exposed to the atmosphere, and cool, creating a vacuum effect. For these reasons, regular potato chips have high oil contents, ranging from 35% to 39%, and even as high as 42%.
The oil content of potato chips is important for many reasons. Oil is a costly raw material and is an important determinant of chip cost. From the standpoint of good nutrition, it is desirable to maintain a low level of oil in chips. A high oil content not only is costly to the processor but often renders the chips greasy or oily and hence, less desirable to consumers. On the other hand, it is possible to make chips so low in oil that they lack flavor and seem harsh in texture.
Chip producers generally are interested in making acceptable chips of lower oil contents than the 35%-39% norm. A large segment of the population, particularly those of middle age and older, is generally interested in reducing its intake of both fats and calories. Moreover, the relative and absolute size of this segment of the population is increasing.
Accordingly, in recent years the art has begun to recognize the desirability of reducing the oil content of potato chip products from both nutritional and cost standpoints. However, past attempts at producing low oil content chips have not been commercially successful, since any significant reduction in oil content has come at the expense of the desired organoleptic properties, particularly as to taste and texture.
Thus, for example, the process disclosed in U.S. Pat. No. 4,277,510 to Wicklund et al. teaches the reduction of oil content to about 30% by weight by the steps of treating peeled potatoes with boiling water or steam to gelatinize surface starch, cutting the treated potatoes to 0.03-0.1 inch slices having moisture contents about 70%, drying with heated air to an average moisture content of about 30-65% by weight, heating the slices with steam under conditions which prevent substantial rehydration, and then frying in oil to produce chips having an oil content of approximately 30% by weight. The pre-drying of the product in the Wicklund patent results, however, in a "glassy"-textured, case hardened product which has a raw, green flavor which is different in taste and texture from regularly fried potato chips.
Similarly, processes such as that disclosed in the British Patent Publication No. 1,519,049 of AB Svenska Foodco, which treat potato chips which have been conventionally fried in oil to a moisture content of approximately 2% with superheated steam to remove surface oil, have generally not been successful in reducing the oil content to desired levels while at the same time meeting organoleptic standards.
High moisture content fried potato products, particularly frozen french fried potatoes, have been treated with hot, moist vapor or saturated steam, as in U.S. Pat. No. 3,627,535, of Davidson et al. and U.S. Pat. No. 4,269,861, of Caridis et al., to remove surface oil after frying in a deep oil bath. The french fries are not, however, subjected to drying thereafter since their shelf stability is dependent upon frozen or refrigerated storage prior to serving, rather than upon drying to a shelf stable chip product. Moreover, french fried potato products are obviously substantially different in moisture content, and in texture and taste characteristics, from fried potato chip products.